Re: The HTTP Sec-From Header (draft-abarth-origin)

draft-abarth-origin-05  features this ABNF..

      origin            = "origin" ":" OWS [ "null" / origin-list ] OWS
      origin-list       = serialized-origin *( 1*SP serialized-origin )
      serialized-origin = scheme "://" host [ ":" port ]
       ; <scheme>, <host>, <port> productions from RFC3986

..with provisio that it is "...ABNF [RFC5234] grammar..."

However, I cannot find the production for <OWS> in either 
draft-abarth-origin-05 or  [RFC5234].

Also, why is serialized-origin delimited explicitly by spaces ( 1*SP ) and not 
simply whitespace e.g. 1*WSP ?  where <WSP> is from [RFC5234]..

          WSP            =  SP / HTAB
                                 ; white space

?

=JeffH